In wood logging operations, labour costs constitute a growing concern among operators. For instance, the slopewise transportation of tree trunks usually comprises a sky-line extending between an upper and a lower base anchor, a carriage suspended from the skyline and a dragline extending through the carriage, then along the skyline and driven by a hoist at the upper anchor base. An operator is always required at said upper anchor base, to pay out and retrieve the drag line which serves to drag the cut trees and also to move the carriage along the skyline.